Exploring the Relationship Between the CORS Program and Regional Real Time GNSS Networks

1. Exploring the Relationship Between the CORS Program and Regional Real Time GNSS Networks Richard Snay & Neil Weston NOAA’s National Geodetic Survey Gavin Schrock Washington State Reference Network Trimble’s GPSNet User Group Meeting Westminster, CO May 9, 2006

2. Material contained in this presentation represents ideas of a few individuals. Some of these ideas have yet to be adopted as official U.S. Government policy. Disclaimer

3. Everyone is able to know where they are and where other things are anytime, anyplace!

4. Continuously Operating Reference Stations (CORS)

5. Network contained 920+ sites as of Apr 2006 Growing at rate of 15 sites per month More than 175 organizations participate in the CORS program Provides code range (C/A, P1, P2) and carrier phase observations (L1, L2) CORS OVERVIEW

6. Postmission Static Positioning (cm-level accuracy with a few hours of data, dm-level accuracy with one minute of data) Postmission Kinematic Positioning (dm-level accuracy for an aircraft, a boat, or a land vehicle) Geophysics / Crustal Motion Meteorology / Water Vapor in Atmosphere Space Weather / Free Electrons in Ionosphere CORS APPLICATIONS

8. CORS Partners: Private Industry “ If you want to see where GPS is going, then keep your eye on the GPS manufacturers.” Bill Strange Former Manager National CORS Program Many GPS companies have developed software that provides their customers with automatic access to CORS data for postprocessing activities.

9. Pass the positions, NOW!! Real-Time Mantra

10. Land surveying Remote sensing / photogrammetry Hydrography Machine control (construction, precision agriculture) Emergency response Asset inventory Applications for 1- 5 cm Real-Time Positioning

11. Structural integrity monitoring (dams, bridges, critical facilities) Atmospheric monitoring (ionospheric & tropospheric modeling, weather forecasting) Tsunami & volcanic warning system (detecting seismic waves) Real-Time Applications(continued)

12. LIDAR images of Manhattan before and after 11 SEP 2001 These images are computerized visualizations of elevation information of the World Trade Center from before (July 2000) and after (September 15, 2001) the attack. These maps were produced using an airborne LIDAR (Light Detection and Ranging) system. The LIDAR system creates detailed and highly accurate elevation information by the precise timing of thousands of laser pulses striking the ground surface. These data can be manipulated in the digital environment to create an array of maps and views of the project site and to obtain precise measurements of structures, debris fields, and other vital information. These images were generated by EarthData (www.earthdata.com), and the aircraft was positioned using CORS data from the NJI2 site which is operated by the New Jersey Institute of Technology. CORS data used to position aircraft

14. Precision Agriculture

15. Hourly Forecast of Precipitable Water

16. Defining and providing access to the National Spatial Reference System (sanctioning adopted positional coordinates, velocities) Developing standards and guidelines Coordinating activities of the various regional networks (promote compatibility) Accrediting the various regional networks (monument stability, multipath environment) Assessing performance (monitoring data quality) NOAA/NGS Support for Regional Real-Time Networks

17. Collect, archive, and distribute selected GNSS data from regional real-time networks to support post-processing applications (Also, encourage network operators to do likewise) That is, NOAA/NGS would incorporate selected real-time sites into the traditional CORS network NOAA/NGS would NOT rebroadcast the GNSS data from regional networks in real time NOAA/NGS Support for Regional Real-Time Networks

18. NOAA/NGS would publicly stream GNSS data (not correctors) via the Internet for ~ 200 federally-funded sites These sites may include elements of the NDGPS, WAAS, NOAA, and PBO networks Anticipated intersite spacing = 200 km in CONUS Regional real-time networks may use the NOAA/NGS-provided data to calibrate and/or enhance their services (which typically require an intersite spacing of about 50 km) If NOAA/NGS is to understand the intricacies of providing real-time data, then the agency needs to be intimately involved in the process These data are being federally funded (for other purposes), and they should be made publicly available for accurate real time positioning NOAA/NGS Support for Regional Real Time Networks

19. High Accuracy Site Nationwide Differential GPS Network

20. Wide Area Augmentation System (WAAS)

21. Plate Boundary Observatory

22. NOAA/NGS would stream auxiliary information to the public via the Internet: Satellite ephemerides Satellite clock parameters Ionospheric models Tropospheric models NOAA/NGS Support for Regional Real-Time Networks

23. NOAA/NGS would study temporal variations in positions (seasonal, daily, ocean loading, atmospheric loading, subsidence, tectonic, etc.) NOAA/NGS would study phenomena affecting accurate positioning (satellite orbits, refraction, multipath, antenna calibration, geoid, etc.) NOAA/NGS Support for Regional Real-Time Networks

24. It is important to realize that the regional real-time networks would not constitute a “navigation service” as defined by the U.S. Government, nor would the NOAA/NGS network. That is, these networks would not meet all “safety-of-life” requirements. These networks, however, would complement rigorous navigation services, such as the NDGPS and WAAS programs, by providing a 1 – 5 cm real-time positioning capability. Not a Navigation Service

25. Immediately after a person has collected a couple hours of GNSS data at a single location, this person could submit these data to OPUS to obtain highly accurate positional coordinates for his/her location in minutes. This capability assumes the person has Internet access and that NGS receives a real-time data feed from a few CORS located near to the person’s location. Benefit: the person would know whether or not he/she observed suitable data before leaving the location. A Special Application of Real-Time Data to Postprocessing

26. Promote accurate and reliable real-time positioning services that are consistent with the National Spatial Reference System, whether these services are being provided by a public or commercial organization. NOAA/NGS Goal for Real-Time Positioning